When President Trump signed an executive order temporarily banning travel from seven majority Muslim countries, he hurled us back to one of the darkest and most shameful chapters of American history. Executive orders that go after specific groups under the guise of protecting the American people are not only unconstitutional, but morally wrong. My father, and so many other Americans of Japanese descent, were targets of just such an order during World War II.

Seventy-five years ago on Sunday, under President Franklin D. Roosevelt’s Executive Order 9066, all people of Japanese ancestry living on the West Coast were forced to leave their homes and report to incarceration camps. Two-thirds were American citizens. Fred Korematsu, my father, then 23, refused to go. A proud and loyal citizen, he had tried to enlist in the National Guard but was rejected and was wrongly fired from his job as a welder in an Oakland, Calif., shipyard He was arrested and tried for defying the executive order. Upon conviction, he was held in a horse stall at a hastily converted racetrack until he and his family were moved to a desolate camp in Topaz, Utah. My father told me later that jail was better than the camp.

He appealed his conviction to the Supreme Court. In his case, and in cases brought by Minoru Yasui and Gordon Hirabayashi — among the most infamous cases in American legal history — the court in 1944 upheld the executive order. Justice Frank Murphy vehemently opposed the majority decision, writing in a dissenting opinion, “Racial discrimination in any form and in any degree has no justifiable part whatever in our democratic way of life.” In the hysteria of war and racialized propaganda, my father’s citizenship did not protect him. For him and the 120,000 other Japanese-Americans incarcerated during World War II, there was no attempt to sort the loyal from the disloyal.

In 1982, almost 40 years after my father’s conviction, evidence was discovered proving that the wartime government suppressed, altered and destroyed material evidence while arguing my father’s, Yasui’s and Hirabayashi’s cases before the Supreme Court. The government’s claims that people of Japanese descent had engaged in espionage and that mass incarceration was necessary to protect the country were not only false, but had even been refuted by the government’s own agencies, including the Office of Naval Intelligence, the F.B.I. and the Federal Communications Commission.

With that evidence, my father reopened his case. In November 1983, he stood before a Federal District Court judge, Marilyn Hall Patel, and said, “As long as my record stands in federal court, any American citizen can be held in prison or concentration camps without a trial or a hearing.” Judge Patel overturned my father’s conviction, declaring that his case “stands as a caution that in times of distress the shield of military necessity and national security must not be used to protect governmental actions from close scrutiny and accountability.”

Around that time, the federal Commission on Wartime Relocation and Internment of Civilians declared that the Korematsu case had been “overruled in the court of history” and found that my father’s incarceration was based on “race prejudice, war hysteria and a failure of political leadership.”

Although his conviction was vacated, my father was keenly aware that his case was never formally overturned, even though it was widely discredited by scholars and even the courts. He was a quiet, soft-spoken man, but he spent the rest of his life speaking around the country about the government misconduct that led to incarceration, in hopes of preventing it from occurring again. In 1998, President Bill Clinton awarded him the Presidential Medal of Freedom for the brave stand he took against an unjust government action.

In 1991, President George H. W. Bush declared, “The internment of Americans of Japanese ancestry was a great injustice, and it will never be repeated.” But it can happen again. Since my father’s death in 2005, I have taken on his work to remind Americans what happens when our Constitution is ignored in the name of national security. We need to scrutinize Mr. Trump’s executive orders and any other attempts to single out groups for repression. Let us come together to reject discrimination based on religion, race or national origin, and to oppose the mass deportation of people who look or pray differently from the majority of Americans.

“Stand up for what is right,” my father said. “Protest, but not with violence. Don’t be afraid to speak up. One person can make a difference, even if it takes 40 years.”